Flu shots decrease flu-season mortality in HF patients by 50%

By Liz Meszaros, MDLinx
Published March 13, 2018

Key Takeaways

In patients with heart failure (HF), getting an influenza vaccination was associated with a 50% decrease in the risk of death during flu season, according to a study presented at the American College of Cardiology’s 67th Annual Scientific Session on March 10-12 in Orlando, FL.

After this nocuous flu season, that’s good news.

Patients with HF are vulnerable to influenza-related complications such as the worsening of acute HF and secondary infections, including pneumonia. Researchers had previously demonstrated that the risk of flu-related mortality is higher in HF patients.

“It is well known that influenza infection is associated with increased risk for mortality in HF patients,” said lead author and presenter Hidekatsu Fukuta, MD, cardiologist, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan. “Given the high mortality rate and the relatively low influenza vaccination rates in HF patients worldwide, our study supports a wider use of influenza vaccination in HF patients.”

Dr. Fukuta and colleagues conducted this meta-analysis to determine the effect of influenza vaccination on mortality and hospitalization in precisely these patients. They used data from five observational cohort studies from the US, Europe, and Asia, which included a total of 78,882 patients (mean age: 64-75 years; 39%-79% male; follow-up: 1-4 years). No randomized, controlled trials were included.

After their pooled analysis, they found that influenza vaccination was associated with a reduced risk for mortality during both the flu season (RR: 0.52; 95% CI: 0.39-0.69) and non-flu season (RR: 0.79; 95% CI: 0.69-0.90). In addition, influenza vaccination was associated with a lower risk for cardiovascular hospitalization (RR: 0.78; 95% CI: 0.68-0.89) but not with a lower risk for all-cause hospitalization (RR: 1.00; 95% CI: 0.90-1.11) during the flu season.

Within these studies, 26% to 86% of HF patients received the influenza vaccine, a finding that speaks to the wide variability in vaccination rates in this population.

Dr. Fukuta and fellow researchers suggested that this fluctuation may be due to the limited guideline recommendations for flu vaccination in these patients.

The Heart Failure Society of America recommends annual influenza vaccinations for all HF patients without known contraindications. The American College of Cardiology (ACC), the American Heart Association (AHA), and the European Society of Cardiology (ESC), however, did not include any specific recommendations for HF patients in their current guidelines. The Centers for Disease Control and Prevention recommends flu shots for everyone aged 6 months and older every year, and encourages HF patients to stay up to date on their immunizations and talk with their physicians.

Dr. Fukuta called for further studies, which may perhaps show a cause-and-effect correlation that their meta-analysis did not.

“Randomized controlled studies should be planned to confirm our observed potential survival benefit of influenza vaccination in these patients,” concluded Dr. Fukuta.

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